(1) Field of the Invention
The present invention generally relates to a vehicle running management system for managing running states of vehicles which are running in a predetermined lane, and more particularly to a vehicle running management system by which running states of vehicles running in a predetermined lane are detected and running control of each vehicle can be performed based on the detected running states of vehicles located before each vehicle.
(2) Description of the Related Art
In recent years, an automated highway system (AHS) for vehicles has been proposed (see Japanese Patent Laid Open Application No. 8-314541). In the automated highway system, magnetic markers are placed along a lane of a road at predetermined intervals and a magnetic sensor provided in a vehicle which runs on the road detects the magnetic markers. Steering control of the vehicle is performed based on detecting signals from the magnetic sensor so that the vehicle does not go out of the lane. As a result, the vehicle is automatically controlled so as to run within the lane. In addition, vehicles which are running in tandem communicate with each other by radio about information regarding the distance between vehicles (vehicle-vehicle communication). In each vehicle, the running speed is controlled based on the received information so that the distance between the vehicles is maintained at a predetermined value. Further, the vehicles which are automatically controlled as described above communicate by radio with communication terminals placed along the road about information regarding road conditions and running states of the preceding vehicles (vehicle-roadside communication). In each vehicle, based on the received information, the running speed is roughly controlled and driving control for avoiding danger is performed. automatically control a vehicle, the vehicle-vehicle communication is performed, running states of the respective vehicles are monitored (the vehicle running management system) and the following vehicles are informed of the monitored running states of the respective vehicles (the vehicle-roadside communication).
In such an automated highway system for the vehicles, for example, one of the lanes of an express-highway is used as a special lane for the vehicles (hereinafter, referred to as automatic driving vehicles) which are automatically driven based on the information received in the vehicle-vehicle communication and the vehicle-roadside communication, or a special road (e.g., the express-highway) is provided for the automatically driven vehicles. That is, it is not considered that the automatically driven vehicles and normal vehicles which are not automatically driven vehicles are mixed in the same lane or the same express-highway.
However, it is difficult to provide the special lane for the automatically driven vehicles on the express-highway or the special road for the automatically driven vehicles. Thus, the automated highway system should be constructed under a condition in which the automatically driven vehicles and the normal vehicles can be mixed. In this case, the driving control of each of the automatically driven vehicle has to be based on the existence of the normal vehicles which have either communication function nor automatic running control function. Thus, it is necessary to manage running states (a position, a speed and the like) of the normal vehicle starting from a time at which the normal vehicle enters the special lane for the automatically driven vehicle to a time at which the normal vehicle exits the special lane.